Question

What circuit motif allows retinal ganglion cells to respond to small spots of light, but not larger ones? This same motif is used to detect sound intensity differences between your left and right ear.

Answer 1

ANSWER :- ON- and OFF - Centre cells by action potential are the circuit motifs that allow retinal ganglion cells to respond to small spot of light, but not larger ones. These same motifs are used to detect sound intensity differences between your left and right ear.

The retinal ganglion cell(RGC) is the nerve or neuron that are present near the inner surface of the retina if eye. The function of this RGC is to receive the visual information from the photoreceptor by two intermediate neurons :- bipolar cells and retina amacrine cells. These RGC are able to respond to small spots of light but not the larger one because the retina amacrine cells create a function subunit within the ganglion cell layer and making the ganglion cells to observe small dot moving a small distance. These RGC transmitt image forming and non-image forming visual formation from the retina in the form of action potential.

The ganglion cells are the first neuron in the retina that respond with action potential. The response of ganglion cell will depend upon response of the cells that feed into the ganglion cell, these are photoreceptor, the bipolar cells and the various lateral interconnections via horizontal cells and amacrine cells.

The circuit work in RGC is the ON centre cell and OFF center cell. The stimulus when fall on the center of an ON center cell receptive field produces Depolarization and when the firing is increased on the ganglion cell, stimulation of the surround produces a Hyperpolarization and this decrease the firing of the cell.

Both the ON center and the OFF centre RGC respond in opposite way to light in the centre and surrounds of their receptive fields. A high frequency gives strong response and a low frequency gives a weak response. And no response means no action potential.